U.S. patent number 4,095,570 [Application Number 05/717,283] was granted by the patent office on 1978-06-20 for electronic engine control system and method of operation.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Timothy K. Sheffer, Donald D. Stoltman.
United States Patent |
4,095,570 |
Sheffer , et al. |
June 20, 1978 |
Electronic engine control system and method of operation
Abstract
A system for positioning an engine control element has a sensor
measuring a value corresponding to the actual position of the
element, a reference providing a command value establishing the
proper position for the element, an electronic control which
compares the measured value with the command value, and an actuator
including a fluid pressure responsive motor for moving the element
and a pressure regulator directed by the electronic control to
regulate the fluid pressure delivered to the motor and cause the
motor to move the control element to the proper position. The
pressure regulator has a coil energized by the electronic control
and a valve member which floats between a
regulated-pressure-reducing bias caused by the magnetic flux
created in the coil and a regulated-pressure-increasing bias caused
by a varying but uncontrolled pressure differential.
Inventors: |
Sheffer; Timothy K. (Rochester,
NY), Stoltman; Donald D. (Henrietta, NY) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
24881407 |
Appl.
No.: |
05/717,283 |
Filed: |
August 24, 1976 |
Current U.S.
Class: |
123/438; 60/276;
137/116.5; 261/DIG.74; 123/568.27 |
Current CPC
Class: |
F02M
26/58 (20160201); F02M 3/07 (20130101); F02M
26/57 (20160201); F02D 41/067 (20130101); G05D
23/1925 (20130101); F02D 21/08 (20130101); F02D
31/004 (20130101); F02M 1/10 (20130101); F02D
41/0077 (20130101); F02D 41/1484 (20130101); F02B
1/04 (20130101); Y02T 10/47 (20130101); Y02T
10/40 (20130101); Y10S 261/74 (20130101); Y10T
137/261 (20150401) |
Current International
Class: |
F02M
3/07 (20060101); F02M 3/00 (20060101); F02D
41/06 (20060101); F02D 31/00 (20060101); F02D
21/08 (20060101); F02D 21/00 (20060101); F02M
1/00 (20060101); F02M 1/10 (20060101); F02D
41/14 (20060101); G05D 23/19 (20060101); F02B
1/04 (20060101); F02B 1/00 (20060101); F02B
003/00 (); F02M 007/00 (); F02B 033/00 () |
Field of
Search: |
;123/32EE,102,119EC,13R,13D,119A,119F ;60/276,285 ;137/116.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cox; Ronald B.
Attorney, Agent or Firm: Veenstra; C. K.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A system for positioning an engine control element
comprising
an actuator including a fluid motor responsive to a regulated
pressure for moving said element toward a retracted position upon a
decrease in said regulated pressure and toward a projected position
upon an increase in said regulated pressure,
said actuator also including a pressure regulator having a port
adapted to sense low pressure, a bleed adapted to sense higher
pressure, an outlet connected to said motor and combining said
pressures to form said regulated pressure, a floating valve member
regulating said port and said bleed, said valve member having one
end exposed to said higher pressure and an opposite end exposed to
a biasing pressure which varies between said low pressure and said
regulated pressure and being biased by the difference between said
higher pressure and said biasing pressure to close said port and
open said bleed, and a coil surrounding said valve member for
magnetically biasing said valve member to open said port and close
said bleed,
and an electronic control including means for increasing current
through said coil to cause said valve member to open said port and
close said bleed and thus reduce said regulated pressure when said
element must be moved toward said retracted position, for
decreasing current through said coil to cause said valve member to
close said port and open said bleed and thus increase said
regulated pressure when said element must be moved toward said
projected position, and for maintaining sufficient current through
said coil to balance the magnetic bias on said valve member with
the pressure bias on said valve member and cause said valve member
to close both said port and said bleed when said element must
remain stationary.
2. The method of positioning an engine control element comprising
the steps of
moving the element toward a retracted position in response to a
decrease in a regulated pressure and toward a projected position in
response to an increase in the regulated pressure,
sensing low pressure through a port and higher pressure through a
bleed, regulating the port and the bleed with a floating valve
member, and combining the pressures to form the regulated
pressure,
energizing a coil with an oscillating power supply having a
variable pulse width,
biasing the floating valve member in a port-opening and
bleed-closing direction with the magnetic flux created in the coil
and in a port-closing and a bleed-opening direction with a pressure
differential created by exposing one end of said floating valve
member to said higher pressure and by exposing the opposite end of
said floating valve member to a biasing pressure which varies
between said low pressure and said regulated pressure,
measuring a value corresponding to the actual position of the
element,
providing a command value establishing the proper position for the
element,
and increasing the pulse width of the power supply to cause the
valve member to open the port and close the bleed and thus reduce
the regulated pressure when the element must be moved toward the
retracted position to reduce the difference between the measured
value and the command value, reducing the pulse width of the power
supply to cause the valve member to close the port and open the
bleed and thus increase the regulated pressure when the element
must be moved toward the projected position to reduce the
difference between the measured value and the command value, and
maintaining the pulse width to balance the magnetic bias on the
valve member with the pressure bias on the valve member to cause
the valve member to close both the port and the bleed and thus
maintain constant the regulated pressure when the measured value
equals the command value.
3. A system for positioning a control element on an internal
combustion engine having an air induction passage, said system
comprising
an actuator including a pneumatic motor responsive to a regulated
pressure for moving said element toward a retracted position upon a
decrease in said regulated pressure and toward a projected position
upon an increase in said regulated pressure,
said actuator also including a pressure regulator having a port
sensing subatmospheric pressure created in said induction passage,
a bleed sensing atmospheric pressure, an outlet connected to said
motor and combining said pressure to form said regulated pressure,
a floating valve member regulating said port and said bleed, said
valve member having one end exposed to atmospheric pressure and an
opposite end exposed to a biasing pressure which varies between
said induction passage pressure and said regulated pressure and
being biased by the difference between atmospheric pressure and
said biasing pressure to close said port and open said bleed, and a
coil surrounding said valve member for magnetically biasing said
valve member to open said port and close said bleed,
an electronic control including an oscillating power supply having
a variable pulse width for energizing said coil,
sensor means connected to said electronic control for providing a
measured value corresponding to the actual position of said
element,
and reference means connected to said electronic control for
providing a command value establishing the proper position for said
element,
said electronic control also including means for increasing said
pulse width when said command value exceeds said measured value to
cause said valve member to open said port and close said bleed and
thus reduce said regulated pressure thereby causing said motor to
move said element toward said retracted position and said measured
value to approach said command value, for decreasing said pulse
width when said measured value exceeds said command value to cause
said valve member to close said port and open said bleed and thus
increase said regulated pressure thereby causing said motor to move
said element toward said projected position and said measured value
to approach said command value, and for maintaining said pulse
width to balance the magnetic bias on said valve member with the
pressure bias on said valve member when said measured value equals
said command value to cause said valve member to close both said
port and said bleed and thus maintain constant said regulated
pressure thereby causing said motor to hold said element
stationary,
whereby said valve member regulates said port and said bleed to
form a regulated pressure causing said motor to move said element
to the proper position established by said reference means.
4. In an internal combustion engine having an air induction
passage, a throttle in said induction passage, a fuel passage, a
metering orifice in said fuel passage, and a metering rod
associated with said orifice: a system for positioning said
metering rod to control fuel flow through said orifice and thus
control the ratio of air flow through said induction passage to
fuel flow through said fuel passage comprising
an actuator including a pneumatic motor responsive to a regulated
pressure for moving said metering rod into said orifice toward a
lean air-fuel ratio position upon a decrease in said regulated
pressure and out of said orifice toward a rich air-fuel ratio
position upon an increase in said regulated pressure.
said actuator also including a pressure regulator having a port
sensing the pressure in said induction passage downstream of said
throttle, a bleed sensing atmospheric pressure, an outlet connected
to said motor and combining said pressures to form said regulated
pressure, a floating valve member regulating said port and said
bleed, said valve member having one end exposed to atmospheric
pressure and an opposite end exposed to a biasing pressure which
varies between said induction passage pressure and said regulated
pressure and being biased by the difference between atmospheric
pressure and said biasing pressure to close said port and open said
bleed, and a coil surrounding said valve member for magnetically
biasing said valve member to open said port and close said
bleed,
an electronic control including an oscillating power supply having
a variable pulse width for energizing said coil,
sensor means connected to said electronic control for providing a
value corresponding to the actual position of said metering
rod,
and reference means connected to said electronic control for
providing a command value establishing the proper position for said
metering rod,
said electronic control also including means for increasing said
pulse width when said command value exceeds said measured value to
cause said valve member to open said port and close said bleed and
thus reduce said regulated pressure thereby causing said motor to
move said metering rod toward said lean air-fuel ratio position and
said measured value to approach said command value, for decreasing
said pulse width when said measured value exceeds said command
value to cause said valve member to close said port and open said
bleed and thus increase said regulated pressure thereby causing
said motor to move said metering rod toward said rich air-fuel
ratio position and said measured value to approach said command
value, and for maintaining said pulse width to balance the magnetic
bias on said valve member with the pressure bias on said valve
member when said measured value equals said command value to cause
said valve member to close both said port and said bleed and thus
maintain constant said regulated pressure thereby causing said
motor to hold said metering rod stationary,
whereby said valve member regulates said port and said bleed to
form a regulated pressure causing said motor to move said metering
rod to the proper position established by said reference means
during normal operation,
whereby said valve member opens said port and closes said bleed to
equalize said regulated pressure with said induction passage
pressure causing said motor to move said metering rod in accordance
with variations in said induction passage pressure in the event
said power supply continuously energizes said coil,
and whereby said valve member closes said port and opens said bleed
to equalize said regulated pressure with atmospheric pressure
causing said motor to move said metering rod to said rich air-fuel
ratio position in the event said power supply fails to energize
said coil.
5. In an internal combustion engine having an air induction
passage, a throttle in said induction passage, an exhaust passage,
a recirculation passage extending from said exhaust passage to said
induction passage, and an exhaust gas recirculation valve in said
recirculation passage: a system for positioning said exhaust gas
recirculation valve to control the flow of exhaust gases through
said recirculation passage comprising
an actuator including a pneumatic motor responsive to a regulated
pressure for moving said valve toward an open, recirculation
permitting, position upon a decrease in said regulated pressure and
toward a closed, recirculation inhibiting, position upon an
increase in said regulated pressure,
said actuator also including a pressure regulator having a port
sensing the pressure in said induction passage downstream of said
throttle, a bleed sensing atmospheric pressure, an outlet connected
to said motor and combining said pressures to form said regulated
pressure, a floating valve member regulating said port and said
bleed, said valve member having one end exposed to atmospheric
pressure and an opposite end exposed to a biasing pressure which
varies between said induction passage pressure and said regulated
pressure and being biased by the difference between atmospheric
pressure and said biasing pressure to close said port and open said
bleed, and a coil surrounding said valve member for magnetically
biasing said valve member to open said port and close said
bleed,
an electronic control including an oscillating power supply having
a variable pulse width for energizing said coil,
sensor means connected to said electronic control for providing a
value corresponding to the actual position of said exhaust gas
recirculation valve,
and reference means connected to said electronic control for
providing a command value establishing the proper position for said
exhaust gas recirculation valve,
said electronic control also including means for increasing said
pulse width when said command value exceeds said measured value to
cause said valve member to open said port and close said bleed and
thus reduce said regulated pressure thereby causing said motor to
move said exhaust gas recirculation valve toward said open position
and said measured value to approach said command value, for
decreasing said pulse width when said measured value exceeds said
command value to cause said valve member to close said port and
open said bleed and thus increase said regulated pressure thereby
causing said motor to move said exhaust gas recirculation valve
toward said closed position and said measured value to approach
said command value, and for maintaining said pulse width to balance
the magnetic bias on said valve member with the pressure bias on
said valve member when said measured value equals said command
value to cause said valve member to close both said port and said
bleed and thus maintain constant said regulated pressure thereby
causing said motor to hold said exhaust gas recirculation valve
stationary,
whereby said valve member regulates said port and said bleed to
form a regulated pressure causing said motor to move said exhaust
gas recirculation valve to the proper position established by said
reference means during normal operation,
whereby said valve member opens said port and closes said bleed to
equalize said regulated pressure with said low pressure causing
said motor to move said exhaust gas recirculation valve in
accordance with variations in said induction passage pressure in
the event said power supply continuously energizes said coil,
and whereby said valve member closes said port and opens said bleed
to equalize said regulated pressure with said higher pressure
causing said motor to move said exhaust gas recirculation valve to
said recirculation inhibiting position in the event said power
supply fails to energize said coil.
6. In an internal combustion engine having an air induction
passage, a throttle in said induction passage, a fuel supply, cold
enrichment means controlling said fuel supply, and an enrichment
stop for said cold enrichment means: a system for positioning said
stop to control the ratio of air flow through said induction
passage to fuel flow through said fuel supply comprising
an actuator including a pneumatic motor responsive to a regulated
pressure for moving said stop toward a lean air-fuel ratio position
upon a decrease in said regulated pressure and toward a rich
air-fuel ratio position upon an increase in said regulated
pressure,
said actuator also including a pressure regulator having a port
sensing the pressure in said induction passage downstream of said
throttle, a bleed sensing atmospheric pressure, an outlet connected
to said motor and combining said pressures to form said regulated
pressure, a floating valve member regulating said port and said
bleed, said valve member having one end exposed to atmospheric
pressure and an opposite end exposed to a biasing pressure which
varies between said induction passage pressure and said regulated
pressure and being biased by the difference between atmospheric
pressure and said biasing pressure to close said port and open said
bleed, and a coil surrounding said valve member for magnetically
biasing said valve member to open said port and close said
bleed,
an electronic control including an oscillating power supply having
a variable pulse width energizing said coil,
sensor means connected to said electronic control for providing a
value corresponding to the actual position of said stop,
and reference means connected to said electronic control for
providing a command value establishing the proper position for said
stop,
said electronic control also including means for increasing said
pulse width when said command value exceeds said measured value to
cause said valve member to open said port and close said bleed and
thus reduce said regulated pressure thereby causing said motor to
move said stop toward said lean air-fuel ratio position and said
measured value to approach said command value, for decreasing said
pulse width when said measured value exceeds said command value to
cause said valve member to close said port and open said bleed and
thus increase said regulated pressure thereby causing said motor to
move said stop toward said rich air-fuel ratio position and said
measured value to approach said command value, and for maintaining
said pulse width to balance the magnetic bias on said valve member
with the pressure bias on said valve member when said measured
value equals said command value to cause said valve member to close
both said port and said bleed and thus maintain constant said
regulated pressure thereby causing said motor to hold said stop
stationary,
whereby said valve member regulates said port and said bleed to
form a regulated pressure causing said motor to move said stop to
the proper position established by said reference means during
normal operation,
whereby said valve member opens said port and closes said bleed to
equalize said regulated pressure with said induction passage
pressure causing said motor to move said stop in accordance with
variations in said induction passage pressure in the event said
power supply continuously energizes said coil,
and whereby said valve member closes said port and opens said bleed
to equalize said regulated pressure with said higher pressure
causing said motor to move said stop to said rich air-fuel ratio
position in the event said power supply fails to energize said
coil.
7. In an internal combustion engine having an air induction
passage, a throttle in said induction passage, and an idle stop for
said throttle: a system for positioning said stop to control engine
idle speed comprising
an actuator including a pneumatic motor responsive to a regulated
pressure for moving said stop toward a high idle speed position
upon a decrease in said regulated pressure and toward a low idle
speed position upon an increase in said regulated pressure,
said actuator also including a pressure regulator having a port
sensing the pressure in said induction passage downstream of said
throttle, a bleed sensing atmospheric pressure, an outlet connected
to said motor and combining said pressures to form said regulated
pressure, a floating valve member regulating said port and said
bleed, said valve member having one end exposed to atmospheric
pressure and an opposite end exposed to a biasing pressure which
varies between said induction passage pressure and said regulated
pressure and being biased by the difference between atmospheric
pressure and said biasing pressure to close said port and open said
bleed, and a coil surrounding said valve member for magnetically
biasing said valve member to open said port and close said
bleed,
an electronic control including an oscillating power supply having
a variable pulse width for energizing said coil,
sensor means connected to said electronic control for providing a
value measuring actual engine idle speed and thus corresponding to
the actual position of said stop,
and reference means connected to said electronic control for
providing a command value establishing proper engine idle speed and
thus establishing the proper position for said stop,
said electronic control also including means for increasing said
pulse width when said command value exceeds said measured value to
cause said valve member to open said port and close said bleed and
thus reduce said regulated pressure thereby causing said motor to
move said stop toward said high idle speed position and said
measured value to approach said command value, for decreasing said
pulse width when said measured value exceeds said command value to
cause said valve member to close said port and open said bleed and
thus increase said regulated pressure thereby causing said motor to
move said stop toward said low idle speed position and said
measured value to approach said command value, and for maintaining
said pulse width to balance the magnetic bias on said valve member
with the pressure bias in said valve member when said measured
value equals said command value to cause said valve member to close
both said port and said bleed and thus maintain constant said
regulated pressure thereby causing said motor to hold said stop
stationary,
whereby said valve member regulates said port and said bleed to
form a regulated pressure causing said motor to move said stop to
the proper position established by said reference means and thus to
maintain the proper idle speed established by said reference means
during normal operation,
whereby said valve member opens said port and closes said bleed to
equalize said regulated pressure with said induction passage
pressure causing said motor to move said stop in accordance with
variations in said induction passage pressure in the event said
power supply continuously energizes said coil,
and whereby said valve member closes said port and opens said bleed
to equalize said regulated pressure with atmospheric pressure
causing said motor to move said stop to said low idle speed
position in the event said power supply fails to energize said
coil.
8. A system for positioning a control element on an internal
combustion engine having an air induction passage, said system
comprising
an actuator including a pneumatic motor responsive to a regulated
pressure for moving said element toward a retracted position upon a
decrease in said regulated pressure and toward a projected position
upon an increase in said regulated pressure,
said actuator also including a pressure regulator having a port
sensing subatmospheric pressure created in said induction passage,
a bleed sensing atmospheric pressure, an outlet connected to said
motor and combining said pressures to form said regulated pressure,
a floating valve member regulating said port and said bleed, and
valve member having one end exposed to atmospheric pressure and an
opposite end exposed to a biasing pressure which varies between
said induction passage pressure and said regulated pressure and
being biased by the difference between atmospheric pressure and
said biasing pressure to close said port and open said bleed, and a
coil surrounding said valve member for magnetically biasing said
valve member to open said port and close said bleed,
an electronic control including an oscillating power supply having
a variable pulse width for energizing said coil,
sensor means connected to said electronic control for providing a
measured value corresponding to the actual position of said
element,
and reference means connected to said electronic control for
providing a command value establishing the proper position for said
element,
said electronic control also including means for creating an error
signal corresponding to the difference between said measured value
and said command value and means responsive to the sum of
quantities proportional to said error signals and to the time
integral of said error signal for increasing said pulse width when
said command value exceeds said measured value to cause said valve
member to open said port and close said bleed and thus reduce said
regulated pressure thereby causing said motor to move said element
toward said retracted position and said measured value to approach
said command value, for decreasing said pulse width when said
measured value exceeds said command value to cause said valve
member to close said port and open said bleed and thus increase
said regulated pressure thereby causing said motor to move said
element toward said projected position and said measured value to
approach said command value, and for maintaining said pulse width
to balance the magnetic bias on said valve member with the pressure
bias on said valve member when said measured value equals said
command value to cause said valve member to close both said port
and said bleed and thus maintain constant said regulated pressure
thereby causing said motor to hold said element stationary,
whereby said valve member regulates said port and said bleed to
form a regulated pressure causing said motor to move said element
to the proper position established by said reference means.
Description
This invention relates to an electronic engine control system and
method of operation and, more particularly, to a system having and
a method employing a practical actuator which cooperates with an
electronic control to position an engine control element.
There are widely recognized potential advantages in a system having
an electronic microprocessor programmed to provide a command value
establishing the proper position for an engine control element
under each combination of engine operating conditions. A system
having such a microprocessor cannot be adopted, however, until a
practical actuator is available to move the engine control element
to the position established by the microprocessor. In such a
system, the actuator must meet the usual criteria of minimum cost,
complexity and space requirement and in addition must draw as
little power and create as little heat as possible.
This invention provides an electronic engine control system
employing an actuator which meets these criteria. In this system
the actuator includes a fluid pressure responsive motor which moves
the engine control element and a pressure regulator which is
directed by an electronic control to regulate the fluid pressure
delivered to the motor in the manner required to cause the motor to
move the control element to the proper position.
A distinguishing feature of the actuator in this system, and a
feature which provides numerous advantages, is a floating valve
member which forms the moving component of the pressure regulator.
The pressure regulator has a port sensing low pressure and a bleed
sensing higher pressure, and the floating valve member regulates
flow through the port and the bleed to form a regulated pressure
for the fluid motor. A coil energized by the electronic control
creates magnetic flux biasing the floating valve member to open the
port and close the bleed and thus reduce the regulated pressure,
while a pressure differential from one end to the opposite end of
the floating valve member biases it to close the port and open the
bleed and thus increase the regulated pressure. The electronic
control varies the current through the coil, preferably by
energizing the coil with an oscillating power supply having a
variable duty cycle or pulse width, to vary the magnetic bias on
the floating valve member, but the pressure bias on the floating
valve member is entirely uncontrolled. Thus the floating valve
member is not located as a fixed function of the duty cycle but
instead is located by varying the duty cycle as required to counter
the uncontrolled pressure bias.
This invention accordingly provides an electronic engine control
system and method of operation which obviates both the need for
precise calibration of the actuator to the electronic control and
the need for compensation of the electronic control to avoid
changes due to age or disturbances such as temperature or voltage
fluctuations.
Moreover, in this system the actuator has a pressure regulator in
which a floating valve member closes both the low pressure port and
the higher pressure bleed when the control element is in the proper
position.
This invention accordingly provides an electronic engine control
system and method of operation which does not require continuous
fluid flow through the port and/or the bleed during steady state
operation and avoids the inefficiencies which would accompany a
continuous flow requirement.
In a preferred embodiment, the actuator includes a pneumatic motor
responsive to subatmospheric pressure and a pressure regulator
which senses subatmospheric engine manifold pressure at the port
and atmospheric pressure at the bleed to form the regulated
pressure for the pneumatic motor. The additional advantages of this
embodiment will be appreciated when it is realized that many engine
control elements are usually positioned by a pneumatic motor
responsive to manifold pressure and have a limit position as
manifold pressure approaches atmospheric pressure -- for in the
event the electronic control were to continuously energize the
pressure regulator coil, the floating valve member would open the
manifold pressure port and close the atmospheric pressure bleed and
the motor then would move the engine control element in accordance
with variations in manifold pressure, while in the event the
electronic control failed to energize the pressure regulator coil,
the floating valve member would close the manifold pressure port
and open the atmospheric pressure bleed and the motor then would
move the engine control element to the limit position.
This invention accordingly provides an electronic engine control
system and method of operation which permits at least limited
engine operation despite improper functioning of the electronic
control.
The details as well as other features and advantages of this
invention are set forth in the remainder of the specification and
are shown in the drawings in which:
FIG. 1 is a schematic diagram of a preferred embodiment of this
electronic engine control system, showing the details of the
pressure regulator and the electronic control;
FIG. 2 illustrates an application of the FIG. 1 embodiment to
control of a carburetor metering rod and is a schematic sectional
elevational view of a carburetor containing the actuator together
with a coil which senses the position of the metering rod;
FIG. 3 is a schematic diagram of a sensor circuit which converts
the variable inductance of the FIG. 2 position sensing coil to a
valve measuring the actual position of the metering rod;
FIG. 4 illustrates an application of the FIG. 1 embodiment to
control of an exhaust gas recirculation valve and is a sectional
elevational view of an exhaust gas recirculation valve assembly
containing the actuator together with a coil which senses the
position of the exhaust gas recirculation valve;
FIG. 5 illustrates an application of the FIG. 1 embodiment to
control of a carburetor choke cold enrichment stop and is a
schematic elevational view of a carburetor having a pneumatic motor
positioning the stop; and
FIG. 6 illustrates an application of the FIG. 1 embodiment to
control of a carburetor throttle idle stop and is a schematic
elevational view of a carburetor having a pneumatic motor
positioning the stop.
Referring first to FIG. 1, an actuator 2 (including a fluid
pressure responsive motor 4 and a pressure regulator 6) positions a
control element 8 on an engine 10. For purposes of illustration,
engine 10 will be considered as an Otto-cycle internal combustion
engine.
A sensor 12 measures a characteristic of operation of engine 10 --
either the position of control element 8 or some other
characteristic controlled by the position of element 8. For
example, where element 8 is a carburetor metering rod, sensor 12
could measure the position of the metering rod or it could measure
a characteristic such as the induction system air-fuel ratio, the
partial pressure of oxygen in the exhaust gases, or the timing of
peak combustion pressure, each of which is controlled by the
position of the carburetor metering rod. Similarly, if element 8
were an exhaust gas recirculation valve, sensor 12 could measure
the position of the valve or it could measure a characteristic such
as the timing of peak combustion pressure which is controlled by
the position of the exhaust gas recirculation valve. Also, if
element 8 were a cold enrichment stop for a carburetor choke or
other cold enrichment device, sensor 12 could measure the position
of the stop or it could measure a characteristic such as the
induction system air-fuel ratio, the exhaust gas oxygen content, or
the timing of peak combustion pressure, each of which is controlled
by the position of the cold enrichment stop during some modes of
engine operation. Further, if element 8 were a valve controlling
the flow of secondary air to the exhaust system, sensor 12 could
measure the position of the valve or it could measure a
characteristic such as the partial pressure of oxygen in the
exhaust gases which is controlled by the position of such a valve.
In addition, sensor 12 could measure engine idle speed which is
controlled by the position of a throttle idle stop. Thus it will be
appreciated that a variety of engine control elements -- both those
mentioned and others -- may be positioned by actuator 2, and that
numerous characteristics of operation of engine 10 -- both those
listed and others -- could be measured by sensor 12, without
departing from the scope of this invention.
Sensor 12 provides a measured value corresponding to the position
of engine control element 8 to an electronic control 14. In
addition, a reference 16 provides a command value establishing the
proper position for element 8 to electronic control 14. While
reference 16 is shown simply as a variable resistor 18, it is
contemplated that reference 16 will in practice be the programmed
memory of an electronic microprocessor which provides a command
value under each combination of engine operating conditions, for
example, under each combination of engine speed and induction
passage manifold pressure.
Within electronic control 14, an amplifier 20 compares the measured
value from sensor 12 with the command value from reference 16 and
creates an error signal corresponding to the difference
therebetween. The error signal is delivered through a circuit
including an amplifier 22 to produce a quantity proportional to the
error signal and a circuit including an amplifier 24 to produce a
quantity proportional to the time integral of the error signal. The
quantities produced by amplifiers 22 and 24 are summed and
delivered through an amplifier 26 to an amplifier 28.
Electronic control 14 also includes an amplifier 30 which forms a
portion of an oscillating power supply producing a 250 Hz square
wave. The output of amplifier 30 is integrated through a circuit
including an amplifier 32 to form a sawtooth wave which is
delivered to amplifier 28. Amplifier 28 converts the sawtooth wave
to a square wave having a pulse width controlled by the output of
amplifier 26. This variable pulse width square wave is delivered
from amplifier 28 through power transistors 34.
In the preferred embodiment, fluid pressure responsive motor 4 is a
pneumatic motor which responds to a regulated subatmospheric
pressure formed in pressure regulator 6. Pressure regulator 6 has a
floating valve member 40 which regulates a port 42 sensing
subatmospheric induction passage manifold pressure (VAC) through a
fitting 44 and a bleed 46 sensing atmospheric pressure (ATM)
through a slot or channel 48 formed in valve member 40 and an
annular space 50 formed about valve member 40.
When floating valve member 40 moves toward the bottom of FIG. 1, a
land 52 exposes port 42 to transmit the low manifold pressure from
fitting 44 through port 42, a chamber 54 surrounding the end 56 of
valve member 40, and an opening 58 to an outlet passage 59 which is
connected through a fitting 60 to motor 4. When floating valve
member 40 moves toward the top of FIG. 1, a land 62 of valve member
40 exposes bleed 46 to transmit the higher atmospheric pressure
through channel 48, annular space 50, and bleed 46 to outlet
passage 59.
It will be appreciated that floating valve member 40 has a pressure
bias toward the top of FIG. 1 -- to close port 42 and open bleed 46
and thus increase the regulated pressure in outlet passage 59 --
because the biasing pressure in chamber 54 about the end 56 of
valve chamber 40 varies between the regulated pressure in outlet
passage 59 and the manifold pressure in port 42 and thus is less
than the atmospheric pressure acting on the other end 64 of valve
member 40. Floating valve member 40 also has a countering magnetic
bias toward the bottom of FIG. 1 -- to open port 42 and close bleed
46 and thus decrease the regulated pressure in outlet passage 59 --
due to the magnetic flux created in a coil 66 which is energized by
the variable pulse width square wave delivered through power
transistors 34 of electronic control 14. Upon an increase in pulse
width or duty cycle, the average current through coil 66 increases
to increase the magnetic flux biasing valve member 40 toward the
bottom of FIG. 1.
Floating valve member 40 slides in a sleeve 68 which contains port
42, bleed 46 and opening 58 and which forms a portion of the flux
path for coil 66. The flux path is completed by a washer 70
contacting sleeve 68, an outer cylinder 72 contacting washer 70,
and a washer 74 contacting cylinder 72 and forming an air gap 76
with valve member 40. Sleeve 68 is received in a spool 78 on which
coil 66 is wound, and sleeve 68, spool 78 with coil 66, washer 70,
cylinder 72 and washer 74 are formed as a subassembly and then
supported in a housing 80 by sleeve 68. Additional support may be
provided across the open end of housing 80 should that be
desired.
In operation, reference 16 provides a command value establishing
the proper position for control element 8. (The command valve may
directly establish the proper position or it may establish the
proper position by establishing the proper value for an engine
operating characteristic controlled by the position of element 8.)
At the same time, sensor 12 provides a measured value corresponding
to the actual position of control element 8. (As discussed above,
the sensor may directly measure the actual position or it may
measure the actual position by measuring an actual engine operating
characteristic controlled by the position of element 8.) If the
command value exceeds the measured value, electronic control 14
increases the duty cycle of coil 66. The increased magnetic flux
created in coil 66 then moves floating valve member 40 toward the
bottom of FIG. 1 to expose port 42 and close bleed 46. Pressure
regulator 6 thus reduces the regulated pressure delivered to motor
4, and motor 4 retracts control element 8 to the proper position
established by reference 16.
Should the measured value from sensor 12 exceed the command value
from reference 16, electronic control 14 reduces the duty cycle of
coil 66. The magnetic flux created in coil 66 is thus reduced, and
the pressure bias on valve member 40 moves valve member 40 toward
the top of FIG. 1 to close port 42 and expose bleed 46. Pressure
regulator 6 thus increases the regulated pressure delivered to
motor 4, and motor 4 projects control element 8 to the proper
position established by reference 16.
When the measured value from sensor 12 equals the command value
from reference 16, electronic control 14 maintains a constant pulse
width. The magnetic flux created in coil 66 which biases valve
member 40 toward the bottom of FIG. 1 is then balanced by the
pressure bias on valve member 40, and valve member 40 closes both
port 42 and bleed 46 to maintain a constant regulated pressure in
outlet passage 59. Accordingly, when control element 8 is in the
proper position, there is no flow through pressure regulator 6.
Other advantages of pressure regulator 6 will be appreciated when
it is understood that valve member 40 is not moved to a particular
position under direct command of electronic control 14 but instead
floats between a magnetic bias created by electronic control 14 and
an uncontrolled pressure bias. Thus this system does not require
calibration of actuator 2 with the duty cycle produced by
electronic control 14 nor does it require compensation of
electronic control 14 to avoid changes due to age or disturbances
such as fluctuations in temperature, voltage, or other conditions
of operation. If engine control element 8 is not in the position
established by reference 16, electronic control 14 simply varies
the duty cycle of coil 66 until control element 8 reaches the
proper position and then maintains the duty cycle necessary to hold
control element 8 in that position.
FIG. 2 illustrates a particular application of this invention.
Here, a carburetor 110 has an air induction passage 112 containing
a choke 113 an a throttle 114. A fuel bowl 116 delivers fuel
through a metering orifice 118 and a fuel passage 120 to a venturi
cluster 122 disposed in induction passage 112; there the fuel is
mixed with air flowing through induction passage 112. A metering
rod 8a controls flow through metering orifice 118 to control the
air-fuel ratio of the mixture in induction passage 112. Metering
rod 8a is carried by a piston 4a which is biased upwardly by a
spring 128 to lift metering rod 8a out of metering orifice 118,
permitting increased fuel flow through orifice 118 and thus
providing a relatively rich air-fuel mixture. Metering rod 8a
corresponds to engine control element 8, and piston 4a together
with spring 128 correspond to motor 4.
Piston 4a is subjected to a subatmospheric regulated pressure
created by a pressure regulator 6a and delivered through an outlet
passage 59a. The manifold pressure (VAC) in induction passage 112
downstream of throttle 114 is delivered to pressure regulator 6a
through a fitting 44a. Pressure regulator 6a is similar in all
important respects to pressure regulator 6 of FIG. 1, and the
similar components have been identified with the same reference
numerals followed by "a" to provide reference to the description of
pressure regulator 6.
Although sensor 12 could measure induction passage air-fuel ratio,
exhaust gas oxygen content or the timing of peak combustion
pressure, each of which is controlled by the position of metering
rod 8a, in this embodiment it is preferred to measure directly the
position of metering rod 8a. For this purpose, piston 4a also
carries a non-magnetic pin 130 which positions an armature 132
within a coil 134 against the bias of a spring 136. As a result,
the inductance of coil 134 indicates the actual position of
metering rod 8a.
Coil 134 is wound on a spool 138 having an extension 140 supported
in carburetor 110. A molded cover 142 surrounds coil 134 and has an
arm 144 receiving a threaded adjusting screw 146. The head 148 of
adjusting screw 146 is trapped below a retainer 150 so that as
adjusting screw 146 is turned, arm 144 of molded cover 142 raises
or lowers coil 134 to provide initial calibration of the position
and thus of the inductance of coil 134. It may be noted that coil
134 is surrounded by the epoxy or thermoplastic of cover 142 and
the zinc of carburetor 110 and thus does not have a constrained
flux path.
FIG. 3 illustrates one embodiment 151 of the circuits available to
convert the variable inductance of coil 134 to a value which may be
delivered to electronic control 14. Coil 134 is connected across
the output of a 11 kHz square wave oscillator formed by amplifiers
152, 154 and 156 and thus converts the square wave to a wave having
a varying decay rate. A circuit including an amplifier 158
integrates the resulting wave and delivers a value measuring the
actual position of metering rod 8a through an amplifier 160 to
electronic control 14 and, if desired, to a position meter 162.
In operation, coil 134, armature 132, and circuit 151 comprise a
sensor 12a which provides a measured value corresponding to the
position of metering rod 8a, and reference 16 provides a command
value establishing a proper position for metering rod 8a. If the
command value exceeds the measured value, electronic control 14
increases the duty cycle of coil 66a. The increased flux created in
coil 66a then lifts floating valve member 40a to expose port 42a
and close bleed 46a. Pressure regulator 6a thus reduces the
pressure delivered to piston 4a, and piston 4a retracts metering
rod 8a into orifice 118 to the leaner air-fuel ratio position
established by reference 16.
Should the measured value from sensor 12a exceed the command value
from reference 16, electronic control 14 reduces the duty cycle of
coil 66a. The magnetic flux created in coil 66a is thus reduced,
and the pressure bias (here acting together with a gravitational
bias) on valve member 40a lowers valve member 40a to close port 42a
and expose bleed 46a. Pressure regulator 6a thus increases the
pressure delivered to piston 4a, and spring 128 lifts piston 4a to
project metering rod 8a out of orifice 118 to the richer air-fuel
ratio position established by reference 16.
When the measured value from sensor 12a equals the command value
from reference 16, electronic control 14 maintains a constant pulse
width. The magnetic flux created in coil 66a which biases valve
member 40a upwardly is then balanced by the downward pressure bias
on valve member 40a, and valve member 40a closes both port 42a and
bleed 46a to maintain a constant regulated pressure in outlet
passage 59a.
It will be appreciated that in the event electronic control 14
continuously energizes coil 66a, floating valve member 40a will
open port 42a and close bleed 46a causing piston 4a to move
metering rod 8a in accordance with variations in manifold pressure.
Thus during low manifold pressure operating conditions piston 4a
would retract metering rod 8a into metering orifice 118 to restrict
fuel flow and provide a lean air-fuel ratio, and during high
manifold pressure operating conditions spring 128 would lift piston
4a to project metering rod 8a out of orifice 118 to increase fuel
flow and provide a rich air-fuel ratio. Moreover, should electronic
control 14 fail to energize coil 66a, floating valve member 40a
would close port 42a and open bleed 46a causing spring 128 to lift
piston 4a and project metering rod 8a out of orifice 118 to the
rich air-fuel ratio position. Thus engine 10 could be operated
despite improper functioning of the electronic control.
FIG. 4 illustrates another application of this invention. Here, an
exhaust gas recirculation (EGR) valve assembly 210 has a valve body
212 forming an EGR passage 214 to interconnect the engine exhaust
passage with the engine air induction passage. An EGR valve 8b
controls the flow of exhaust gases through EGR passage 214 and is
positioned by a valve stem 216 secured to a diaphragm 4b. Diaphragm
4b is biased by a spring 218 to engage EGR valve 8b with a seat 219
and inhibit recirculation of exhaust gases through passage 214. EGR
valve 8b corresponds to engine control element 8, and diaphragm 4b
together with spring 218 correspond to motor 4.
The cover 220 for EGR valve assembly 210 incorporates a pressure
regulator 6b which is similar in all important respects to pressure
regulator 6 of FIG. 1, and the similar components have been
identified with the same reference numerals followed by "b" to
provide reference to the description of pressure regulator 6.
Cover 220 also includes a coil 134b containing an armature 132b
biased by a spring 136b to engage a pin 222 carried by valve stem
216. The varying inductance of coil 134b is employed in circuit 151
of FIG. 3 to provide a value measuring the actual position of EGR
valve 8b.
In operation, coil 134b, armature 132b, and circuit 151 comprise a
sensor 12b which provides a measured value corresponding to the
position of EGR valve 8b, and reference 16 provides a command value
establishing a proper position for EGR valve 8b. If the command
value exceeds the measured value, electronic control 14 increases
the duty cycle of coil 66b. The increased flux created in coil 66b
then moves floating valve member 40b to expose port 42b and close
bleed 46b. Pressure regulator 6b thus reduces the pressure
delivered to diaphragm 4b, and diaphragm 4b retracts EGR valve 8b
away from seat 219 to the open, recirculation permitting, position
established by reference 16.
Should the measured value from sensor 12b exceed the command value
from reference 16, electronic control 14 reduces the duty cycle of
coil 66b. The magnetic flux created in coil 66b is thus reduced,
and the pressure bias on valve member 40b moves valve member 40b to
close port 42b and expose bleed 46b. Pressure regulator 6b thus
increases the pressure delivered to diaphragm 4b, and spring 218
lowers diaphragm 4b to project EGR valve 8b nearer seat 219 to the
position established by reference 16.
When the measured value from sensor 12b equals the command value
from reference 16, electronic control 14 maintains a constant pulse
width. The magnetic flux created in coil 66b which biases valve
member 40b leftwardly is then balanced by the rightward pressure
bias on valve member 40b, and valve member 40b closes both port 42b
and bleed 46b to maintain a constant regulated pressure in outlet
passage 59b.
It will be appreciated that in the event electronic control 14
continuously energizes coil 66b, floating valve member 40b will
open port 42b and close bleed 46b causing diaphragm 4b to move EGR
valve 8b in accordance with variations in manifold pressure. Thus
during low manifold pressure operating conditions diaphragm 4b
would retract EGR valve 8b away from seat 219 to permit exhaust gas
recirculation, and during high manifold pressure operating
conditions spring 218 would cause diaphragm 4b to project EGR valve
8b toward seat 219 to inhibit exhaust gas recirculation. Moreover,
should electronic control 14 fail to energize coil 66b, floating
valve member 40b would close port 42b and open bleed 46b causing
spring 218 to lower diaphragm 4b and engage EGR valve 8b with seat
219, thus inhibiting exhaust gas recirculation. Accordingly, engine
10 could be operated despite improper functioning of the electronic
control.
A fitting 224 allows filtered air to be delivered to bleed 46b.
A second diaphragm 226 of smaller effective area than diaphragm 4b
is disposed below diaphragm 4b, and the chamber 228 therebetween is
exposed through a passage 230 formed in hollow valve stem 216 to
the induction passage manifold pressure (VAC) in recirculation
passage 214 downstream of EGR valve 8b. Diaphragm 226 assures that
EGR valve 8b will close upon a sudden decrease in manifold
pressure, such as may occur during sudden engine deceleration.
The remaining construction of exhaust gas recirculation valve
assembly 210 is similar to that shown in U.S. Pat. Nos. 3,762,384
and 3,800,765.
FIG. 5 shows yet another application of this invention. Here, a
carburetor 110c has an air induction passage 112c containing a
choke 113c and a throttle 114c. Choke 113c serves in a conventional
manner as a cold enrichment device to control the fuel supplied
through carburetor 110c and thus control the air-fuel ratio in
induction passage 112c. A choke lever 240 is secured to choke 113c
and is connected through a choke link 242, an intermediate lever
244, in intermediate shaft 246, an operating lever 248, and a
thermostat link 250 to a choke thermostat 252. Upon a decrease in
temperature, thermostat 252 pulls downwardly on link 250 to
increase the bias on choke 113c toward the closed position
shown.
Operating lever 248 has a slot 254 containing the turned end 8c of
a link 256 extending from the plunger 258 of a vacuum motor 4c. The
end 8c of link 256 acts as a cold enrichment stop which limits
movement of choke 113c toward the closed position. However, slot
254 allows lever 248 to move away from stop 8c, and thus choke 113c
is free to move toward the open position as the force of air flow
on choke 113c overcomes the force of thermostat 252. Cold
enrichment stop 8c corresponds to engine control element 8, and
vacuum motor 4c corresponds to motor 4.
A pressure regulator 6c, identical to pressure regulator 6 of FIG.
1, delivers a regulated subatmospheric pressure to vacuum motor
4c.
Vacuum motor 4c may contain a coil such as 134 or 134b having an
armature such as 132 or 132b which operate with circuit 151 to form
a sensor 12c providing a value measuring the actual position of
cold enrichment stop 8c.
In operation, sensor 12c provides a measured value corresponding to
the position of cold enrichment stop 8c, and reference 16 provides
a command value establishing a proper position for stop 8c. If the
command value exceeds the measured value, electronic control 14
increases the duty cycle of the pressure regulator coil. The
increased flux created in the coil then moves the pressure
regulator floating valve member to expose a manifold pressure port
and close an atmospheric pressure bleed. Pressure regulator 6c thus
reduces the pressure delivered to vacuum motor 4c, and vacuum motor
4c retracts stop 8c to the leaner air-fuel ratio position
established by reference 16, limiting movement of choke 113c toward
the closed position.
Should the measured value from sensor 12c exceed the command value
from reference 16, electronic control 14 reduces the duty cycle of
the pressure regulator coil. The magnetic flux created in the coil
is thus reduced, and the pressure bias on the pressure regulator
valve member moves the valve member to close the manifold pressure
port and expose the atmospheric bleed. Pressure regulator 6c thus
increases the pressure delivered to vacuum motor 4c, and vacuum
motor 4c projects stop 8c to the richer air-fuel ratio position
established by reference 16, permitting further movement of choke
113c toward the closed position.
When the measured value from sensor 12 equals the command value
from reference 16, electronic control 14 maintains a constant pulse
width. The magnetic flux created in the pressure regulator coil is
then balanced by the pressure bias on the pressure regulator valve
member, and the valve member closes both the manifold pressure port
and the atmospheric pressure bleed to maintain a constant regulated
pressure.
It will be appreciated that in the event electronic control 14
continuously energizes the pressure regulator coil, the floating
valve member will open the manifold pressure port and close the
atmospheric pressure bleed causing vacuum motor 4c to move stop 8c
in accordance with variations in manifold pressure. Thus during low
manifold pressure operating conditions vacuum motor 4c would
retract stop 8c to provide a lean air-fuel ratio, and during high
manifold pressure operating condition vacuum motor 4c would project
stop 8c to permit a rich air-fuel ratio. Moreover, should
electronic control 14 fail to energize the pressure regulator coil,
the floating valve member would close the manifold pressure port
and open the atmospheric pressure bleed causing vacuum motor 4c to
project stop 8c to the rich air-fuel ratio position. Thus engine 10
could be operated despite improper functioning of the electronic
control.
FIG. 6 illustrates a further application of this invention. Here, a
carubretor 110d has an air induction passage 112d containing a
choke 113d and a throttle 114d. A throttle lever 280 is secured to
throttle 114d and has an arm 282 adapted for connection to the
usual throttle linkage and throttle return spring. An idle stop 8d
engages throttle lever 280 to limit movement of throttle 114d
toward the closed position and thus control engine idle speed. Stop
8d is connected through a plunger 284 to a diaphragm 4d and is
biased toward the closed throttle, low idle speed position by a
spring 285. Idle stop 8d corresponds to control element 8, and
diaphragm 4d together with spring 285 correspond to motor 4.
The housing 286 for diaphragm 4d has a recess 288 for receiving a
pressure regulator 6d identical to pressure regulator 6b of FIG.
4.
In operation, sensor 12 provides a measured value corresponding to
engine idle speed and thus corresponding to the position of idle
stop 8d, and reference 16 provides a command value establishing
proper engine idle speed and thus establishing a proper position
for stop 8d. If the command value exceeds the measured value,
electronic control 14 increases the duty cycle of the coil in
pressure regulator 6d. The increased flux created in the coil then
moves the floating valve member in pressure regulator 6d to expose
a manifold pressure port and close an atmospheric pressure bleed.
Pressure regulator 6d thus reduces the pressure delivered to
diaphragm 4d, and diaphragm 4d retracts stop 8d to the high idle
speed position established by reference 16.
Should the measured value from sensor 12 exceed the command value
from reference 16, electronic control 14 reduces the duty cycle of
the pressure regulator coil. The magnetic flux created in the coil
is thus reduced, and the pressure bias on the pressure regulator
valve member moves the valve member to close the manifold pressure
port and expose the atmospheric pressure bleed. Pressure regulator
6d thus increases the pressure delivered to diaphragm 4d, and
spring 285 projects stop 8d to the low idle speed position
established by reference 16.
When the measured value from sensor 12 equals the command value
from reference 16, electronic control 14 maintains a constant pulse
width. The magnetic flux created in the pressure regulator coil is
then balanced by the pressure bias on the pressure regulator valve
member, and the valve member closes both the manifold pressure port
and the atmospheric pressure bleed to maintain a constant regulated
pressure.
It will be appreciated that in the event electronic control 14
continuously energizes the pressure regulator coil, the pressure
regulator floating valve member will open the manifold pressure
port and close the atmospheric pressure bleed causing diaphragm 4d
to move stop 8d in accordance with variations in manifold pressure.
Thus during low manifold pressure operating conditions diaphragm 4d
would retract stop 8d to the high idle speed position, and during
high manifold pressure operating condition diaphragm 4d would
project stop 8d to the low idle speed position. Moreover, should
electronic control 14 fail to energize the pressure regulator coil,
the pressure regulator floating valve member would close the
manifold pressure port and open the atmospheric pressure bleed
causing spring 285 to project stop 8d to the low idle speed
position. Thus engine 10 could be operated despite improper
functioning of the electronic control.
* * * * *